THIS IS A LIPOSOMAL COMPLEX. LIPOSOMES SURROUND THE METHYLCOBALAMIN TO ENSURE BIOAVAILABILITY. "Vitamin B12" refers to a group of compounds known as cobalamins. The most common form of vitamin B12 is called "cyanocobalamin." Vitamin B12 in the brain and central nervous system is only present as methylcobalamin, which is why methylcobalamin is the form of vitamin B12 that is called "neurologically active." Your liver has to transform regular vitamin B12 (cyanocobalamin) into methylcobalamin. Vitamin B12 in its active form, methylcobalamin, may give a much better result than other forms which have to be converted into methylcobalamin.*